From a plurk mail in html format, generate a summary

plk-ms.perl

#!/usr/bin/perl -w
# plurk mail summary
#    plurk-sent mail
# => *.mbox (by gmail)
# => *.html (by hypermail)
# => *.txt (by lynx -dump)
# => plk-ms.perl
# e.g.
# hypermail -m plurk.mbox -d plurk
# for f in plurk/????.html ; do lynx -dump $f | perl plk-ms.perl ; done | sort > ~/plurk-summary.txt

use strict;

my ($subj, %count, %month, @keys, $k, $m);

%month = (
    Jan => 1,
    Feb => 2,
    Mar => 3,
    Apr => 4,
    May => 5,
    Jun => 6,
    Jul => 7,
    Aug => 8,
    Sep => 9,
    Oct => 10,
    Nov => 11,
    Dec => 12,
);

while (<>) {
    if ($.==1) {
	$subj = $_;
	next;
    } else {
	++$count{$1} if (m#(https://www.plurk.com/p/\w+)#);
	printf("%02d%02d%02d $4 # ", $3, $month{$2}, $1) if /Date:.*?(\d+)\s+([A-Z]\w\w)\s+20(\d\d)\s+(\d\d:\d\d:\d\d)/;
    }
}

@keys = keys %count;
$m = $keys[0];
for $k (@keys) {
    $m = $k if ($count{$k} > $count{$m});
}
print("$m ") if $#keys >= 0;
print($subj);